JPH09310901A - Controller of air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the current flowing to a compressor driving circuit by so controlling an air conditioner as to enlarge the voltage to be applied to a compressor motor as compared with the time when the frequency of the compressor motor is stable, when the frequency of the compressor motor driven by an inverter is going up or going down. SOLUTION: In an object where the power part of an air conditioner is composed of a diode bridge 1, a reactor 2, a smoothing capacitor 3, a power transistor 4, a DC current sensor 5, a control circuit 6, and a compressor motor 7, when the rotational frequency of the compressor motor 7 is stable, the voltage at time of frequency being stable is applied to the compressor motor 7. But, in case that the rotational frequency changes, the additional components of application voltage are decided by the control circuit 6, and the voltage where it is added is applied to the compressor motor 7. Hereby, no matter how the rotational frequency of the compressor motor 7 may change, this restrains an excessive current from flowing to a compressor driving circuit 8, thus this is protecting the compressor driving circuit 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor motor drive control method using an inverter.

[0002]

2. Description of the Related Art In recent years, in air conditioners, a compressor drive control by an inverter has become mainstream, but the compressor drive circuit is inevitably complicated, and at the same time, it is more easily broken than in the past and the reliability is required. Is coming.

In the past, this type of compressor drive control has generally been configured as shown in Japanese Utility Model Laid-Open No. 63-33393. Hereinafter, the configuration will be described with reference to FIG.

In FIG. 7, the horizontal axis represents the operating frequency of the compressor motor, and the vertical axis represents the voltage applied to the compressor motor 7 corresponding to the designated frequency. Generally, the torque of the compressor motor 7 has been secured by increasing the voltage applied to the compressor motor 7 as the compressor rotation frequency increases.

However, as shown in FIG. 6, when the rotational frequency of the compressor motor 7 changes, an electric current that is originally larger than the ideal electric current will flow.

Further, if the voltage applied to the compressor motor 7 is always set to be high, the current flowing through the air conditioner will decrease, but the magnetic flux of the motor will be saturated, which may result in burnout due to overheating. It was

Further, although the load applied to the compressor motor 7 is different between the cooling operation and the heating operation, the F / V pattern of the compressor motor 7 remains unchanged during the cooling operation and the heating operation. It was

[0008]

In such a conventional air conditioner control device, the rotation frequency of the compressor motor 7 is controlled by the protection control such as the change of the rotation frequency of the compressor motor 7 and the current control and the pressure control. At the lowest frequency,
Originally, since an excessive current flows than the ideal current,
There is a problem that the compressor drive circuit is overloaded and the life of the components used in the compressor drive circuit is shortened.

Further, since an excessive current flows, protection control is applied, the number of continuous operations is reduced, and comfortable air conditioning is impaired.

Further, since the load on the compressor motor 7 is different between the cooling operation and the heating operation, the protection control is more easily applied during the heating operation than during the cooling operation, and as a result,
There was a problem of impairing the comfort of air conditioning.

The present invention is intended to solve such a conventional problem, and it is possible to protect the components of the compressor motor drive circuit, and to reduce the number of times the operation is stopped by the protection control to improve the comfort. An object of the present invention is to provide a control device for an air conditioner that can be operated.

[0012]

In order to achieve the above-mentioned object, the control device for an air conditioner of the present invention has the advantage that when the compressor motor rotation frequency changes, it is more than when the compressor motor rotation frequency is stable. The voltage applied to the compressor motor is increased.

Further, the other means is configured such that the F / V pattern of the compressor motor is set during the cooling operation and during the heating operation, respectively.

Another means is to increase the applied voltage in the F / V pattern of the compressor motor near the lowest frequency used by the compressor motor.

Another means is such that the voltage applied to the compressor motor is changed according to the increment and decrement of the direct current detected by the direct current sensor.

According to the present invention, the parts of the compressor motor drive circuit can be protected, and the number of times the operation is stopped by the protection control can be reduced to improve comfort.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to an F / V pattern which is a recognition of the relationship between an operating frequency F and an applied voltage V when the frequency of a compressor motor driven by an inverter is stable, and an F / V when the frequency of the compressor motor changes. It has a pattern and protects the compressor drive circuit by increasing the voltage applied to the compressor motor when the frequency of the compressor motor is rising and falling, compared to when the frequency of the compressor motor is stable. Therefore, even when the compressor motor rotation frequency changes, an excessive current does not flow in the compressor drive circuit, and the compressor drive circuit can be protected.

Further, the F / V of the compressor motor during the cooling operation
The pattern and the F / V pattern of the compressor motor during heating operation are provided. During heating operation, the voltage applied to the compressor motor is changed compared with during cooling operation to protect the compressor drive circuit. However, even during the heating operation, the load on the compressor drive circuit can be equalized and the compressor drive circuit can be protected.

Further, the outdoor unit is provided with an F / V pattern for protecting the compressor drive circuit when it is stable at the lowest frequency of use of the compressor motor, and when the frequency of the compressor motor becomes close to the lowest frequency of use, the compressor motor is Increase the applied voltage,
This protects the compressor drive circuit, and protects the compressor drive circuit without increasing the current flowing to the compressor drive circuit even if the compressor rotation frequency reaches the lowest usable frequency due to current control. It has the effect of being able to.

Further, the compressor motor I / I which changes the voltage V applied to the compressor motor depending on the load condition of the air conditioner
The V pattern is provided, and the current flowing through the compressor drive circuit can be stabilized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0022]

【Example】

(Embodiment 1) FIG. 1 is a graph showing the voltage applied to the compressor motor 7 when the rotation frequency of the compressor motor 7 changes.

FIG. 5 shows the power section of the air conditioner, which includes a diode bridge 1, a reactor 2, a smoothing capacitor 3, a power transistor 4 and a direct current sensor 5.
The control circuit 6 and the compressor motor 7, and the compressor drive circuit 8 is composed of the power transistor 4 and a part of the control circuit 6.

FIG. 7 shows an F / V pattern similar to that of the conventional example. Next, the operation will be described.

When the rotation frequency of the compressor motor 7 is stable, the voltage obtained from FIG. 7 is applied to the compressor motor 7. However, if the compressor rotation frequency changes,
When the current rotation frequency of the compressor motor 7 is F1, the control circuit 6 determines the applied voltage additional component V2 from the rotation change frequency F2 of the compressor motor 7 and the compressor rotation frequency speed as shown in FIG. The voltage obtained by adding V2 to the compressor motor 7
Apply to. This operation is always performed when the rotation frequency of the compressor motor 7 changes, and when it does not change, the voltage obtained from FIG. 7 is applied to the compressor motor 7.

As described above, according to the control device for an air conditioner of the first embodiment of the present invention, no matter how the rotation frequency of the compressor motor 7 changes, an excessive current does not flow in the compressor drive circuit 8. The compressor drive circuit 8 can be protected.

(Embodiment 2) In FIG. 2, the vertical axis represents the voltage applied to the compressor motor 7, the horizontal axis represents the rotation frequency of the compressor motor 7, 10 is the F / V pattern during the cooling operation, and 11 is the heating operation. F / V pattern at that time, Fs is the lowest frequency used in the compressor, and Fmin is the lowest frequency of the compressor motor 7 under the conditions at that time.

As shown in FIG. 2, since the load applied to the compressor motor 7 is different between the heating operation and the cooling operation, it is applied to the compressor motor during the cooling operation rather than the voltage applied to the compressor motor during the heating operation. By setting the voltage higher, the load applied to the compressor drive circuit 8 is made equal during the cooling operation and the heating operation.

Depending on the type of air conditioner, the load applied to the compressor motor 7 during heating operation may be larger than during heating operation, or the load during cooling operation may be larger. The F / V pattern 10 may become the F / V pattern 11 during heating operation.

As described above, according to the controller of the air conditioner of the second embodiment of the present invention, the load applied to the compressor drive circuit 8 is made equal during the cooling operation and the heating operation, and the compressor drive circuit 8 is protected. can do.

(Embodiment 3) The rotation frequency of the compressor motor 7 is lowered due to current control, etc.
When the rotation frequency of No. 1 is lowered to the minimum frequency Fmin only, the current flowing in the compressor drive circuit 8 which is originally ideal becomes larger than the ideal current due to the load state of the air conditioner. Therefore, as shown in FIG. 3, the applied voltage to the compressor motor 7 in the vicinity of Fmin is increased, and the compressor drive circuit 8
It reduces the current flowing through.

As described above, according to the controller for the air conditioner of the third embodiment of the present invention, even if the rotation frequency of the compressor motor 7 becomes the minimum frequency Fmin due to current control or the like, the current flowing through the compressor drive circuit 8 is reduced. It is possible to protect the compressor drive circuit 8 without increasing

(Embodiment 4) As shown in FIG. 5, when the direct current sensor 5 detects the current flowing in the compressor drive circuit 8, when the direct current detected by the direct current sensor 5 is increased, As shown, the voltage applied to the compressor motor 7 is increased and the current flowing through the compressor drive circuit 8 is decreased.

As described above, according to the control device for an air conditioner of the fourth embodiment of the present invention, the current flowing through the compressor drive circuit 8 can be stabilized regardless of the load state of the compressor motor 7. Therefore, the compressor drive circuit 8 can be protected.

[0035]

As is apparent from the above embodiments, according to the present invention, the compressor motor applied voltage is determined from the compressor motor rotation change frequency and the compressor rotation frequency speed. An air conditioner control device can be provided that can stabilize the current flowing through the compressor drive circuit even when the frequency changes.

Further, since the F / V pattern during the cooling operation and the F / V pattern during the heating operation are set respectively, the load applied to the compressor drive circuit regardless of whether the operation mode is cooling or heating. Can be made equivalent.

Since the voltage applied to the compressor motor near the lowest frequency is increased, the current flowing through the compressor drive circuit is not increased even when Fmin is reached, and the compressor drive circuit can be protected.

Further, since the voltage applied to the compressor motor is changed by the current flowing through the compressor drive circuit, the current flowing through the compressor drive circuit is stabilized regardless of the load condition of the compressor motor. It is possible to protect the compressor drive circuit.

[Brief description of drawings]

FIG. 1 is an F / of a compressor of an air conditioner according to a first embodiment of the present invention.
Diagram showing V pattern

[Fig. 2] F / of a compressor of an air conditioner according to a second embodiment of the present invention
Diagram showing V pattern

FIG. 3 is an F / V of a compressor of an air conditioner according to a third embodiment of the present invention.
Illustration showing the pattern

[Fig. 4] Fig. 4 shows an I / V of a compressor of an air conditioner of Example 4 of the present invention
Diagram showing V pattern

FIG. 5 is a power circuit diagram of the outdoor unit of the air conditioner according to the first and fourth embodiments of the present invention.

FIG. 6 is a diagram showing output current data when a compressor motor frequency of a conventional air conditioner changes.

FIG. 7 is a diagram showing an F / V pattern of a compressor of the air conditioner.

[Explanation of symbols]

 7 Compressor motor 8 Compressor drive circuit 10 F / V pattern during cooling operation 11 F / V pattern during heating operation

Claims (4)

[Claims] 1. An F / V pattern (hereinafter, simply referred to as an F / V pattern), which is a recognition of a relationship between an operating frequency F and an applied voltage V when a frequency of a compressor motor driven by an inverter is stable, and a frequency change of the compressor motor. When the frequency of the compressor motor is rising and falling, the voltage applied to the compressor motor is increased to increase the voltage applied to the compressor motor when the frequency of the compressor motor rises and falls. Air conditioner control device with circuit protection. 2. An F / V pattern of the compressor motor during cooling operation and an F / V pattern of the compressor motor during heating operation are provided, and the voltage applied to the compressor motor during heating operation is different from that during cooling operation. An air conditioner control device that protects the compressor drive circuit. 3. An outdoor unit is provided with an F / V pattern for protecting the compressor drive circuit when stable at the lowest frequency of use of the compressor motor, and when the compressor motor frequency is close to the lowest frequency of use, the compressor motor is An air conditioner control device that protects the compressor drive circuit by increasing the applied voltage. 4. A control device for an air conditioner, which comprises a compressor motor I / V pattern that changes a voltage V applied to the compressor motor according to a load state of the air conditioner, and protects a compressor drive circuit.